Oxygen Vacancies-rich Manganese Oxide with Flower-like Nanosheets for High Performance Supercapacitors

Here, flower-like manganese oxide with enriched oxygen vacancies were reported for high performance supercapacitors. The moderate oxygen-vacancy were achieved by controlling annealing atmosphere. Benefiting from improving the conductivity and the density of active sites, MnO_x?Ar sample as an electrode material has remarkable specific capacity (339 mAh g^?1 at 0.5 A g^?1), extraordinary rate capability (90 % capacity retention at 1 A g^?1), and good cycling property (90 % capacity retention at 1 A g^?1 after 5000 cycles). Additionally, the asymmetric supercapacitor (ASC) was assembled which used the MnO_x?Ar sample as cathode and Kochen Black (KB) as anode, which displayed a remarkable energy density (16 Wh kg^?1) at a large power density (7593 W kg^?1). These results, on the one hand, further expand the application of MnO₂-based materials, and on the other hand, offer a new perspective for the oxygen non-stoichiometry in material electrochemistry.